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CountDownLatch.scala
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CountDownLatch.scala
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/*
* SPDX-License-Identifier: Apache-2.0
* Copyright 2016-2024 Daniel Urban and contributors listed in NOTICE.txt
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package dev.tauri.choam
package async
import cats.~>
import cats.syntax.all._
import cats.effect.std.{ CountDownLatch => CatsCountDownLatch }
sealed abstract class CountDownLatch[F[_]] { self =>
def release: Axn[Unit]
def await: F[Unit]
def toCats: CatsCountDownLatch[F]
def mapK[G[_]](f: F ~> G): CountDownLatch[G] = {
new CountDownLatch[G] {
final def release: Axn[Unit] =
self.release
final def await: G[Unit] =
f(self.await)
final def toCats: CatsCountDownLatch[G] =
self.toCats.mapK(f)
}
}
}
object CountDownLatch {
def apply[F[_]](count: Int)(implicit F: AsyncReactive[F]): Axn[CountDownLatch[F]] = {
(Ref.padded(count), Promise.apply[F, Unit]).mapN { (c, p) =>
new CountDownLatch[F] { self =>
final val release: Axn[Unit] = {
c.getAndUpdate { ov =>
if (ov > 0) ov - 1
else ov
}.flatMapF { ov =>
if (ov == 1) p.complete.provide(()).void
else Axn.unit
}
}
final def await: F[Unit] = {
p.get
}
final def toCats: CatsCountDownLatch[F] = {
new CatsCountDownLatch[F] {
final def release: F[Unit] =
F.run(self.release)
final def await: F[Unit] =
self.await
}
}
}
}
}
}